"Next inspection due" labels

[davesparks]

Therefore by saying it is not due for inspection until the date shown (e.g 5 years), is that not implying that it is safe?

No it is not implying it is safe, it is stating what the recommended date for the next inspection is.
The next inspection date sticker doesn't imply anything about the safety of the installation, it tells you when it was last inspected and the maximum recommended time period before the next inspection.

With this thought in mind, lately I have not been replacing any "next inspection due" stickers/dates until the installation is satisfactory.

Then you are not complying with BS7671